“If you consider yourself a great act, and you haven’t been at the Apollo, then you haven’t been at the ultimate proving ground,” explains Harvey, host of the new “Showtime at the Apollo.”

Nearing the May 24 finale episode of the revived talent show-style series, Harvey has seen enough to know the no-holds-barred audience isn’t for the faint of heart.

Judging is entirely up to the group of self-declared critics. If they cheer, the performer makes it to the finale for the chance to win a residency at the theater; if they boo, the Sandman Raphael Thomas (originally Howard Sims) removes the act from the stage.

“When you rub that log as a contestant on ‘Showtime at the Apollo,’ you’re at the mercy of one of the toughest crowds on planet Earth. I mean, it’s really, really a tough crowd,” he says, referring to the “good luck” Tree of Hope that’s rubbed by all performers.

Harvey notes the past season has brought out some pretty impressive talent, including NYC periodontist Matthew Hashimoto, “one of the best voices” he’s heard. But, still, countless acts have gotten the boot because they don’t understand the “rules” of the Apollo.

What rules? Harvey says there are a few off-limit artists that performers “can’t do at the Apollo unless you do it exact,” including Whitney Houston, Michael Jackson, Prince, Luther Vandross and Mariah Carey.

“If you miss a note, we know it, and you’re gone,” he says. “You can’t do Mariah Carey. No one does Chaka Khan. No one. Don’t even attempt Chaka Khan. Those are the rules.”

The guidelines come from the theater’s Amateur Night contests, the first of which took place more than 84 years ago. A performer’s chance to show his or her skills on a stage that’s been graced by Billie Holiday, Ella Fitzgerald and countless others isn’t to be taken lightly.

The theater is “world-famous” and “legendary,” Harvey explains, “it’s where dreams are made.”

Harvey himself credits the theater with helping launch his career, now marked by juggling hosting gigs, on shows like “Little Big Shots” (NBC) and “Family Feud” (ABC), with his daytime talk show “Steve.”

The comedian now fondly recalls his first time performing at the theater, but nearly 27 years ago, he was feeling quite different.

Near age 37, he was living in his car and was able to afford his way from Florida to NYC with the help of a friend and a $99 flight deal.

“It was probably one of the scariest nights I’ve ever had,” he recalls. “I went out, got a standing ovation and my television career was born.”

He continues: “It was actually my first television appearance as a stand-up. I met, that night, some guy named Jamie Foxx… We introduced ourselves to each other; this was ’91, I think, ’90, ’91. We were both not famous at all. We sat there and performed that night.”

Much has evolved behind the landmarked theater’s doors and within the Harlem neighborhood where it lives since Harvey first stepped foot on stage. While the area and its inhabitants may look different, Harvey notes their enthusiasm has remained.

“ … Harlem has changed — you go during the week when we do the show, Thursday and Friday mornings, it’s like 50-50 black-white. That was never the case back in the ‘90s,” he says. It’s the late-night weekend shows where “you get more of the authentic Harlem crowd.”